The nature of rearrangements leading to plastic deformation have been investigated over several years, as a step in developing a description of plasticity in amorphous solids. Early work by Argon and co-workers [1]} attempted to understand such rearrangements by considering disordered bubble rafts as tractable model systems for glasses. These investigations indicated that under shear deformation, plastic rearrangements involved the participation of a small number of bubbles. These localised rearrangements have been termed shear transformations, and have been subsequently observed in numerous computer simulations and experiments [2]}, [3]}, [4]}, [5]}, [6]}. A schematic view, obtained from computer simulations of a two dimensional glass model [2]} is shown in Figure REF . Although one may envisage circumstances where plastic deformations may not be so localised, and will not occur as isolated events (see Ref. [8]} for a recent review and detailed discussion), the idea of localised shear transformations or shear transformation zones (STZ) underlies many lines of modeling plasticity. Unlike dislocations in crystals, such STZs do not have a well defined structural characterization, nor does one a priori have the ability to identify locations where plastic events will occur. Considerable effort has been directed therefore at arriving at ways of identifying the locations of plastic events, based on an analysis of local structure, energies, local yield stress, soft modes, etc. [9]}, [10]}, [11]}, [12]}, [13]}, including the deployment of machine learning approaches [14]}, [15]}. However, the possibility of predicting with high reliability the locations of plastic events remains a subject of ongoing exploration.
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